Students 3D print pink robotic prosthetic arm for a 13-year-old girl

Students at the Washington University in St. Louis has built a robotic prosthetic arm for thirteen-year-old Sydney Kendall who lost her right arm in a boating accident when she was six years old.

Using a computer program and a 3D printer, Kendall Gretsch, Henry Lather and Kranti Peddada, seniors studying biomedical engineering in the School of Engineering & Applied Science, created a robotic prosthetic arm out of bright-pink plastic. Each part of the robotic hand and arm is made individually. It took about 20 minutes to print the small parts, and an hour to make larger parts. The whole project took about 13-15 hours to print. Total cost is only $200, while normally a prosthetic would cost a minimum of $6,000.

The students developed the robotic hand as part of their engineering design course with associate professor of physical therapy Joseph Klaesner. With guidance from several medical practitioners including orthopedic hand surgeons Charles A. Goldfarb and Lindley Wall, they built the prosthetic out of bright-PINK plastic, as request by Sydney.

"They brought their engineering expertise, and we shared our practical experience with prosthetics and the needs of children," Goldfarb wrote in a recent blog post about the project. "It was a valuable experience as Kendall, Henry and Kranti had no prosthetic experience and were able to think about the issues in a very different way."

After the accident, Sydney learned to write with her left hand, but found most tasks difficult to accomplish with her prosthetic arm. On the other side, the new 3D printed arm is very easy to manipulate. By moving her shoulder, she can direct the arm to throw a ball, move a computer mouse and perform other tasks.

Peddada said it was thrilling to observe Sydney use her arm. "It really showed us the great things you can accomplish when you bridge medicine and technology," Peddada said.

Sydney's new arm has motor and working thumb, which set it apart from similar "Robohand" that has been widely adopted. A sensor worn on the shoulder detects motion, and sends a signal through a cord to a micro controller chip which activates little motors that control the fingers and thumb. The prosthetic is powered by a nine volt battery.

As Sydney grows, the prosthetics need to be replaced with larger devices to accommodate her body changes. But with 3D printing, this problem can be easily solved. "With the 3-D printer, a prosthetic can be made much less expensive. The possibilities of what can be done to improve prosthetics using this technology is very exciting." said Sydney's mother, Beth Kendall.